Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

Pull powerpc fixes from Benjamin Herrenschmidt:
 "It looks like my rewrite of our lazy irq scheme is still exposing
  "interesting" issues left and right.  The previous fixes are now
  causing an occasional BUG_ON to trigger (which this patch turns into a
  WARN_ON while at it), due to another issue of disconnect of the lazy
  irq state vs the processor state in the idle loop on pseries and
  cell.

  This should fix it properly once for all moving the nasty code to a
  common helper function.

  There's also couple more fixes for some debug stuff that didn't build
  (and helped resolving those problems so it's worth having), along with
  a compile fix for newer gcc's."

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  tty/hvc_opal: Fix debug function name
  powerpc/numa: Avoid stupid uninitialized warning from gcc
  powerpc: Fix build of some debug irq code
  powerpc: More fixes for lazy IRQ vs. idle

1 files changed, 47 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 1b415027ec0e..1f017bb7a7ce 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -229,7 +229,7 @@ notrace void arch_local_irq_restore(unsigned long en)
 	 */
 	if (unlikely(irq_happened != PACA_IRQ_HARD_DIS))
 		__hard_irq_disable();
-#ifdef CONFIG_TRACE_IRQFLAG
+#ifdef CONFIG_TRACE_IRQFLAGS
 	else {
 		/*
 		 * We should already be hard disabled here. We had bugs
@@ -286,6 +286,52 @@ void notrace restore_interrupts(void)
 		__hard_irq_enable();
 }
 
+/*
+ * This is a helper to use when about to go into idle low-power
+ * when the latter has the side effect of re-enabling interrupts
+ * (such as calling H_CEDE under pHyp).
+ *
+ * You call this function with interrupts soft-disabled (this is
+ * already the case when ppc_md.power_save is called). The function
+ * will return whether to enter power save or just return.
+ *
+ * In the former case, it will have notified lockdep of interrupts
+ * being re-enabled and generally sanitized the lazy irq state,
+ * and in the latter case it will leave with interrupts hard
+ * disabled and marked as such, so the local_irq_enable() call
+ * in cpu_idle() will properly re-enable everything.
+ */
+bool prep_irq_for_idle(void)
+{
+	/*
+	 * First we need to hard disable to ensure no interrupt
+	 * occurs before we effectively enter the low power state
+	 */
+	hard_irq_disable();
+
+	/*
+	 * If anything happened while we were soft-disabled,
+	 * we return now and do not enter the low power state.
+	 */
+	if (lazy_irq_pending())
+		return false;
+
+	/* Tell lockdep we are about to re-enable */
+	trace_hardirqs_on();
+
+	/*
+	 * Mark interrupts as soft-enabled and clear the
+	 * PACA_IRQ_HARD_DIS from the pending mask since we
+	 * are about to hard enable as well as a side effect
+	 * of entering the low power state.
+	 */
+	local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
+	local_paca->soft_enabled = 1;
+
+	/* Tell the caller to enter the low power state */
+	return true;
+}
+
 #endif /* CONFIG_PPC64 */
 
 int arch_show_interrupts(struct seq_file *p, int prec)